Wi-Fi and other technologies that operate on unlicensed and/or lite-licensed spectrum such as Citizens Broadband Radio (3.5 GHz Band, see FCC Rulemaking 12-354) has advantages over legacy designed licensed cellular networks when operating a facilities based network including: cost and ability to utilize spectrum nationwide; reduced infrastructure costs (e.g. inexpensive and highly flexible access points vs. expensive stationary cellular towers and proprietary radio access network equipment); more flexible design criteria and superior data speed when in close range when compared to legacy cellular technology. Wi-Fi and other unlicensed or lite-licensed use in supporting what have been traditionally primary cellular devices, called mobile stations, is thus positioned to disrupt an industry that is ripe for change. As used herein, it is understood that unless particular features of the IEEE-802.11 family of standards are being exploited, that reference to WiFi also contemplates use of other wireless radio frequency, infrared, and optical digital communication technologies.
Wi-Fi is growing fast. U.S. consumers are near some type of Wi-Fi more than 80% of the time they connect to the Internet on a mobile device. Global hotspots have grown to over 7.1 million in 2015 from 4.2 million in 2013. Initiatives like CableWiFi and Hotspot 2.0 are making Wi-Fi more readily available and easier to connect to. Further, operating systems such as current Android, CyanogenMod and Apple IOS supporting smartphones are now designed to, with carrier permission settings on the device, use data connectivity for voice, SMS and MMS thus allowing Wi-Fi to replace the primary need for legacy licensed network infrastructure to be used to support mobile stations.
Wi-Fi First refers to the operation of a mobile network where mobile stations use a managed Wi-Fi network or other unlicensed or lite-licensed network protocol as the primary network for talk, text and data, and only use expensive cellular networks to fill the gaps. This type of service aligns much more closely to consumer behavior and enables disruptive business models which are poised to change the wireless industry forever. Wi-Fi First also positions the multi-service operators (MSOs) and existing campus and enterprise networks to play a significant role in the future design, sales, servicing and deployment of mobile stations, whereas today they are largely being pushed aside by the large Mobile Network Operators (“MNO”) via business practices designed to limit market entry and innovation when large MNOs utilize unlicensed and lite-licensed spectrum. The large MNO's support an alternative technology described as LTE-U which, as a prerequisite for deployment and use, requires the concurrent use of a licensed network along-side an unlicensed network, and also removes management and control of the unlicensed spectrum and its supported applications when using a mobile station from the MSO and/or campus/enterprise networks.
Unlike LTE-U, LTE-PW or WiFi First managed networks permissively share control of LTE capable mobile stations with the MSO and or campus enterprise network, thereby creating a more valuable service and network.
Two equations can be used to quantify in mathematical terms the total utility or societal value of interconnected networks based on a concept commonly described as “Network Effects.” The first is called “Metcalf's Law” and the second is “Reed's law.”
Robert Metcalf was the first to describe a “Network Effect.” He theorized that that each added Node (“n”) to a network becomes more valuable. Metcalfe's law states that the value of a network is proportional to the square of the number of connected users of the system, thus a network becomes far more valuable from a societal vantage point as it gets larger, approximating n2. Whether the exponent is two is not critical; it generally accepted that the value of communication node as a result of connection to a communications network does not decrease, and the value and functionality of the network increases at least as the reach of the network increases.
David Reed followed up by asserting that Metcalf's expression was correct in concept, but it undervalued the aggregate network by not capturing the value from what are known as Group Forming Networks. Reed theorized that each “n” is not just part of one network; it is in fact part of multiple different groups of subnetworks within the larger whole, and the value is represented by the sum value of all these subgroups within the whole. Therefore, the whole far exceeds the value calculated by Metcalf. One way to think about a Group Forming Network is having a node on the larger network “join” with other nodes on the network that have a common interest. The mathematical expression of Reed's Law is 2n.
The primary difference in the Network Effect is that Metcalf's law scales quadratically, but Reed's scales exponentially. The advent of Social Networks (Facebook) and Business Networks (LinkedIn) networks within the larger “Internet” (which has always been known as a “network of networks”) have basically proven Reed's extension. Reed's extension means that while D is functionally zero for two node-networks, D is on the order of 1030 for just 100 nodes. For a realistic N, the number is truly astronomical. That is why, despite the intuitive nature of the postulates behind Metcalf and Reed, some still dismiss the idea that simply adding a single N to an existing network can double (or increase the exponent of) the value of the “Network” as a whole.
The principal criticism is that they assume that each N leads to equal value and benefit when that is not true. The mathematical equations measure potential contact but the greatest social utility comes from actual contact rather than mere potential contact. Some users may not be present on the network or able to navigate the process when communication seeks them or they want to make contact. Some users may not have desired content. Some users' Nodes may not have adequate bandwidth to the network. Some networks may be cost prohibitive to the point that the cost of adding the node outweighs the value added by that node. In addition, a single added “node” may not have a one-to-one relationship with each user. For example one FAX machine may serve 50 workers, while the second one serves 25 and the fourth one only 12, with the result that an additional FAX connection will correspond to a wide variety of user groups and thus contacts. Likewise, in social networks, if users that join later use the network less than early adopters, then the benefit of each additional user may lessen, making the overall network less efficient if costs per users are fixed. Finally, some argue that both Reed's Law and Metcalfe's Law overstate network value because they fail to account for the restrictive impact of human cognitive limits on network formation which implies a limit on the number of inbound and outbound connections a human in a group-forming network can manage, with the result that the actual maximum-value structure is much sparser than the set-of-subsets measured by Reed's law or the complete graph measured by Metcalfe's Law.
Most of these arguments reduce to a point regarding the relative inefficiency (e) of the “Node” or the network(s). Reduced to its mathematical properties by assuming inefficient users and networks are a combined “e”; a revised Metcalf's Law reads (N−e)*(N−e−1), and a revised Reed's Law 2n-e.
Over the last decade, many of these anecdotally described “nodal” inefficiencies of the “nodes” have been and are being overcome by technology advancements. For example, Google greatly assists the ability of any ordinary person to become a network whiz in locating other nodes. From a network perspective, Google, and many other user friendly focused software and hardware companies are node amplifiers that elevate the ordinary person from only being able to receive and send email to a selected few to being able to surf (web-aided by Google), watch (Netflix), add content (YouTube), conduct commerce (E-Bay, Amazon, etc.), and communicate (Skype) as a fully functioning node. This clearly has the effect of reducing the “negative value” of “e” when applying to the Metcalf concept. More importantly, these advancements also move the value of the “Internet” to the Reed model, by enabling the edge to self-form and self-identify the sub-groups it wishes to join. The easier a user can join groups, form groups, and manage additions to its group, the more group forming a network becomes, and thus the more value it represents.
As these self-forming networks evolve and become more sophisticated, they begin to replace the original applications for which the original network was built and designed. For example, VoIP has replaced landline phone, video streaming has replaced network and cable TV. But they evolve as well. “Video” was originally one-to-many broadcast but is now increasingly many-to-many (e.g., YouTube). On the other hand, in order to be able to conduct voice conversations a user had to have a publicly-available telephone number within the global numbering system and as a consequence the user was able to reach and be reached by the entire universe of people on the world-wide public switched network that used the global numbering system. Many of the relatively recent “group” networks on the Internet, however, do not directly address using the global IP and domain name system. They employ higher-layer addresses (like a Skype ID or an internal LinkedIn ID or Facebook Username) to directly communicate—with the result that the group becomes more insular and resides within something akin to a walled garden. The latter outcomes attenuate the friction reduction to “e” and once again reduce the network effects.
A device or node must first connect to a host network before it can potentially access the full functionality of the Internet, or, more often, access to a sub-group network of the Internet. Since they functionally serve as a bottleneck last mile access network providers can and do often try to exercise considerable control over what users can do.
Some network providers also impose restrictions and/or costs on the users of the network that also serve to limit total network utility and therefore value. In response, some national or multi-national regulators have responded to these efforts by the legacy network service providers efforts to shape the evolution through limits or rationing how Internet applications and devices can be used. For example, the FCC's Net Neutrality Rules implemented a policy that preserves users' and edge providers' ability to self-form and self-identify associational groups. In essence, the FCC recognized that an “Edge Controlled” network has a far greater public utility than a centrally controlled network of the resulting “virtuous cycle” of innovation and use and then value creation without needing to obtain permission from the entity providing last mile network access and who has the most incentive and ability to deny permission until the edge shares some of the resulting added value with the last mile provider. The FCC imposed rules mandating mostly “neutral” management of the Internet access portion, with the result that the access provider judge or prioritize individual specific uses of the network over others in order to capture pecuniary gains over and above the simple cost of providing network access and fulfilling basic network demand.
“Net neutrality” rules reduce the incentive for broadband networks to increase their intelligence in the core of the network and apply a type of created resistance to, or interference with, access to and through their network. In the network build-out model prior to FCC Net Neutrality, this purposeful injection of rules could be described as an internet “Ω”, leading to a network value of 2n−Ω according to the Metcalf analysis. In this model a large network provider would insert a measure of control and resistance technically outside of the Edge's control, reducing the value of the Internet to the Edge.
Prior to Net Neutrality, the business plan of many large network operators was to sell back the Ω to the certain applications, making those applications more valuable at the “Edge.” An Example would be in prioritizing the “Netflix” video stream over a “Hulu” video stream. In essence the network provider would create a type of scarcity and then charge to have the scarcity removed.
For the last several years technologies such as “deep packet inspection” (DPI)—when modified and used within the packet “core” of a network through what is known as “Policy and Charging Rules Function” (PCRF)—have been deployed in choke points in the various networks. This is particularly so with regard to Mobile Broadband Providers (MBPs), who have gone the farthest with implementing DPI-based control, and who also have relief or exemptions from many of the so called “Net Neutrality” rules imposed by the FCC. Data is collected by the MBP at these choke points and that then allow the MBP to become application and service aware in order for the MBP to be able to manage the delivery of some services through prioritization over other services and applications in return for payments.
The MBP's focus on control and management of the network coupled with the expectation of ration-based toll points at the location where resource demand is greater than supply reinforces the natural incentive a company with market power has to ration rather than increase available supply at the choke point because the net profit is higher than would be obtained if supply is increased but the price is allowed to go toward incremental cost.
While the FCC's net neutrality rules now make many business plans that rely on choke point rationing far more difficult, the MBPs' response, however, has not been quite what the FCC desired. Rather than move to open networks and price for only access and demand the major providers have begun to consolidate through mergers or teaming and through attempts to control what has been termed the “Eco-System” additional controls or types of the a From a technical perspective they have found ways to push “Ω” out from just the core more towards the edge while still finding new ways to implement rationing and differential charges based on application or service, or the group forming network that is being used. This is most obvious from the MBPs' industry-wide cooperative creation and implementation of what are known as “LTE-U” and LTE-LAA,” and the some specific network outcomes of the recently announced “5G” initiatives coupled with access and use limitations written into software that controls mobile stations' ability to freely switch from fully-licensed to quasi-licensed or unlicensed spectrum when using data-based services and applications, including voice and many of the freshly imagined M2M and IoT applications. The plain goal is the re-imposition of scarcity for network resources even though, in reality, abundant network resources exist. The scarcity is, however, artificial since there are alternative network resources available that could be easily accessed if the MBPs' cartel-like standards-based or software restrictions can be avoided or removed.
The new scarcity takes many forms. Some network access design requires software on the phone to favor using Cell Towers instead of smaller Nodes or non MBP operated distributed antenna systems of femtocells. So called voluntary industry groups try to establish and enforce geographic licensing restrictions in order to use a technology (which is the case for LTE-U and LTE-LAA). The larger providers require device manufacturers through unique “certification” processes to limit the device's functions through customizations in the OS (even though the hardware and software often still technically resides in the device to enable unlicensed use). Devices are often tied to individual providers—each with their own self-imposed limits that in many instances survive unlocking and porting requirements that may have been imposed by regulators. The larger MNOs use similar scarcity based pricing models for applications and bandwidth for both retail and wholesale relationships through adhesion-based business practices. Compatible use of unlicensed spectrum is not only tied to and only works with concurrent use of licensed spectrum under the current LTE-U and LTE-LAA designs, but also prohibits and/or interferes with the actual network management of the unlicensed spectrum by the MSO, campus or enterprise network when a competing small MNO uses the unlicensed network. So called efforts attempting to impose “listen before talk” techniques do not actually address the fact that the network control of the unlicensed spectrum is being tied to the licensed network management, it only reduces the incidents of encroachment. All of these restrictions contribute to creating artificial restrictions on access between a mobile station and another edge point or node via control asserted by the access network host.
The FCC's net neutrality rules have led to additional unintended consequences. While they prohibit some DPI/PCRF network management for express gain, the FCC has unintentionally dampened investment in the ability for groups to “manage” their own network resources via coordinated access between the core, the network nodes and the mobile station. When artfully managed with DPI and PCRF type functions data, voice, video and texting can be fully enabled and allowed to become more flexible and more valuable through a direct and cooperative grant of delegation and control to the individual sub-groups who can then co-manage their own sub-networks and the devices attached to that sub-network.
LTE is powerful. When the 3GPP began to document its goals for LTE it stated:
“The following are the main objectives for LTE:                Increased downlink and uplink peak data rates.        Scalable bandwidth        Improved spectral efficiency        All IP network        A standard's based interface that can support a multitude of user types.        
LTE networks are intended to bridge the functional data exchange gap between very high data rate fixed wireless Local Area Networks (LAN) and very high mobility cellular networks.”
However, the current wielding of some LTE initiatives such as the LTE-U initiative appears to change the original purpose of LTE to instead design a use that allows imposition of scarcity. LTE can maintain spectrum dependence for some use cases, but it can also encourage and allow spectrum flexibility if the operator of the core chooses to fully adopt the open network principles and policies behind the FCC's net neutrality rules and again re-embraces the original intent of LTE, namely “to bridge the functional data exchange gap between very high data rate Local Area Networks (LAN) and very high mobility cellular networks.”
FIG. 6A shows a prior art Evolved Packet System LTE system diagram.
The Evolved Packet System (EPS) contains following network elements:
UE: The User Equipment.
Evolved UTRAN (eNodeB): The eNodeB supports the LTE air interface and includes following functions:
Functions for Radio Resource Management: Radio Bearer Control, Radio Admission Control, Connection Mobility Control, Dynamic allocation of resources to UEs in both uplink and downlink (scheduling);
Selection of an mobility management entity (MME) at UE attachment when no routing to an MME can be determined from the information provided by the UE;
Routing of User Plane data towards Serving Gateway;
Scheduling and transmission of paging messages (originated from the MME);
Scheduling and transmission of broadcast information (originated from the MME or O&M);
Measurement and measurement reporting configuration for mobility and scheduling.
Mobility Management Entity (MME): The MME manages mobility, UE identities and security parameters. It includes following functions:
Non Access Stratum (NAS) signaling and security;
Idle mode UE reachability (including control and execution of paging retransmission);
Tracking Area list management (for UE in idle and active mode);
PDN GW and Serving GW selection;
MME selection for handovers with MME change;
Roaming; (terminating S6a towards home HSS)
Authentication;
Bearer management functions including dedicated bearer establishment.
Serving Gateway (SGW): The Serving Gateway is the node that terminates the interface towards EUTRAN. For each UE associated with the EPS, at a given point of time, there is one single Serving Gateway. Functions include:
Packet Routing and Forwarding
The local Mobility Anchor point for inter-eNB handover;
E-UTRAN idle mode downlink packet buffering and initiation of network triggered service request procedure;
E-UTRAN idle mode downlink packet buffering and initiation of network triggered service request procedure;
Accounting on user and QoS Class Identifier (QCI) granularity for inter-operator charging;
UL and DL charging per UE, PDN, and QCI.
End marker handling
Packet Filtering with TFT
PDN Gateway (PGW): The PGW is the node that terminates the SGi interface towards the PDN. If a UE is accessing multiple PDNs, there may be more than one PGW for that UE. The PGW provides connectivity to the UE to external packet data networks by being the point of exit and entry of traffic for the UE. The PGW performs policy enforcement, packet filtering for each user, charging support, lawful Interception and packet screening. PDN GW functions include:
Mobility anchor for mobility between 3GPP access systems and non-3GPP access systems. This is sometimes referred to as the SAE Anchor function.
Policy enforcement (gating and rate enforcement)
Per-user based packet filtering (by e.g. deep packet inspection) Charging support
Lawful Interception (out of scope for phase 4) UE IP address allocation
Packet screening
Transport level packet marking in the downlink;
DL rate enforcement based on APN Aggregate Maximum Bit Rate (APN-AMBR)
PCRF: PCRF is the policy and charging control element. PCRF functions include:
Policy (QoS and gating) control
Charging control
In non-roaming scenario, there is only a single PCRF in the HPLMN associated with one UE's IP-CAN session. The PCRF terminates the Gx, Gxc and Gxa interfaces.
Evolved Packet System (EPS) contains following network elements:
S1-C: Reference point for the control plane protocol between E-UTRAN and MME.
S1-U: Reference point between E-UTRAN and Serving GW for the per bearer user plane tunnelling and inter eNodeB path switching during handover.
S5: It provides user plane tunneling and tunnel management between Serving GW and PDN GW. It is used for Serving GW relocation due to UE mobility and if the Serving GW needs to connect to a non-collocated PDN GW for the required PDN connectivity.
S6a: It enables transfer of subscription and authentication data for authenticating/authorizing user access to the evolved system (AAA interface) between MME and HSS.
Gx: It provides transfer of (QoS) policy and charging rules from PCRF to Policy and Charging Enforcement Function (PCEF) in the PDN GW. The interface is based on the Gx interface.
Gxa It provides transfer of (QoS) policy information from PCRF to the Trusted Non-3GPP accesses.
Gxc It provides transfer of (QoS) policy information from PCRF to the Serving Gateway
S9: It provides transfer of (QoS) policy and charging control information between the Home PCRF and the Visited PCRF in order to support local breakout function.
S10: Reference point between MMEs for MME relocation and MME to MME information transfer.
S11: Reference point between MME and Serving GW
SGi: It is the reference point between the PDN GW and the packet data network. Packet data network may be an operator external public or private packet data network or an intra operator packet data network, e.g. for provision of IP Multimedia subsystem (IMS) services. This reference point corresponds to Gi for 3GPP accesses.
X2 The X2 reference point resides between the source and target eNodeB.
FIG. 5 shows a prior art state transition diagram for user equipment. Upon power on, the enterprise mobility management (EMM) state is deregistered, the radio resource control (RCC) is in idle mode, the UE location is unknown, the mobility mode is based on the public land mobile network (PLMN) cell selection, and data communication is off. After registration and bearer setup, the EMM is registered, the RCC is connected, the UE location is E-Node B, the mobility mode is in a handover mode, and data communication is on. After data inactivity, the the mobile terminal remains registered, the RCC is in idle mode, the UE location is based on a TA list, the mobility mode is in cell reselection mode, and data communication is in standby. Data activity reverts the mobile communication device to Active UL/DL data mode.
FIG. 7 shows a prior art LTE initial call setup diagram.
System Acquisition: UE performs frequency synchronization and reads MIB/SIBs from PBCH to acquire system information. It then camps on the most suitable cell.
RRC Connection Setup: The UE and eNodeB exchange signaling to set up an RRC connection. The UE then sends RRC Connection Setup Complete message to the eNodeB.
Attach Request: The UE includes in the ATTACH REQUEST message a valid GUTI together with the last visited registered TAI, if available. If there is no valid GUTI available, the UE shall include the International Mobile Subscriber Identity (IMSI) in the ATTACH REQUEST message.
eNodeB forwards the Attach Request message (including: Message Type, eNB UE ID, TAI, CGI etc.) to the MME.
Identity Procedure: In the case of the first Attach, MME sends an Identity Request to the UE. Identity procedure is required only if attach request contains GUTI/last-TAI and the TAI is not local to MME
The UE responds with Identity Response including Mobile Identity that is set to IMSI.
Authentication/Security: In case of initial attach when there is no UE context on the network, authentication is performed. The MME sends an Authentication Information Request to the HSS and receives an Authentication Information Answer which is used to send Authentication Request to the UE. Authentication procedure is optional. UE then sends an Authentication Response to the MME
Update Location Request: The MME sends the Update Location Request including the IMSI. The HSS replies with Update Location Answer. Subscription Data shall be present when the Result is Success.
Create Session Request: The MME sends a Create Session Request to SGW which is followed by confirmation.
Initial Context Setup Request/Attach Accept: Attach Accept is sent as NAS PDU in the Initial Context Setup (Message Type, E-RAB ID, QoS parameters, Transport Layer Address, NAS-PDU, UE Security Capabilities, Security key) from MME to eNodeB.
Attach Accept message contains new GUTI if the attach request contained IMSI or foreign/non-local GUTI. This completes Attach Request.
Security procedure and UE Capability exchange is then performed.
RRC Connection Re-configuration: The eNodeB sends the RRC Connection Reconfiguration message including the EPS Radio Bearer Identity to the UE, and the Attach Accept message to the UE. The APN is provided to the UE for which the activated default bearer is associated.
Initial Context Setup Response: The eNodeB sends Initial Context Setup Response to the MME
Uplink Information Transfer: The UE sends an Uplink Information Transfer message. This message includes the Attach Complete message for MME
Attach Complete: eNodeB encapsulates the Attach Complete message and transfers it to MME.
Modify Bearer Message: One receiving both Context Setup Response and Attach Complete, the MME sends a Modify Bearer Request to SGW. SGW sends the response and starts sending the DL packets.
FIG. 8 shows a prior art LTE initiated UE detach diagram.
UE can be detached either from Idle or Connected mode. If it is Idle, RRC connection setup is completed before detach message.
UE sends Detach Request message to MME which responds with confirmation after exchanging Delete Session messages with SGW.
FIG. 9 shows a prior art LTE initial call MME initiated detach diagram.
Delete session request can be send when UE is in Idle or Connected mode. If a UE is in Idle mode, it may be paged. MME exchanges Delete Session messages with SGW. Detach request is conditional on successful page to the UE.
FIG. 10 shows a prior art LTE active to idle mode transition diagram.
User inactivity is detected based on parameter settings (Inactivity timer). eNB requests MME to release the UE Context. MME then informs SGW that UE is no longer available for DL traffic by sending Modify Bearer Request message. After getting the response from SGW, MME sends Context Release command to eNB. After responding to MME, eNB releases RRC Connection.
FIG. 11 shows a prior art LTE Network Initiated Idle to Active Transition diagram.
Incoming data from PGW is forwarded to SGW which notifies MME be sending Downlink data notification. After acknowledgement MME pages all eNBs in the TA by sending the Paging message to these eNBs. The eNBs pages the UE in all cells in the TA.
If the UE receives the page, it responds by initiating the UE Triggered Connection Re-activation.
FIG. 12 shows a prior art LTE UE Initiated Service Request diagram.
UE reads the system information broadcast in the cell and performs DL/UL synchronization.
UE then requests RRC Connection setup. Once completed, eNB then forwards NAS Service Request in Initial UE Message to MME. MME then carries out Authentication process (optional) and requests eNB to establish the S1 UE context. eNB then activates security functions.
Later Radio Bearers are setup to support EPS bearers in RRC Connection Reconfiguration messages.
After successfully establishing the bearers, eNB responds to the MME with Initial Context Setup Response MME then sends Modify Bearer Request to update SGW with IP address etc. for the DL of the user plane.
FIG. 13 shows a prior art LTE S1 Based Inter eNodeB Handover diagram.
Based on UE reports, source eNB decides to initiate S1-based handover to target eNB if there is no X2 connectivity to target eNB.
eNB sends Handover Required (handover type, target Id, cause etc.) message to MME.
MME verifies that source SGW can continue to serve UE and sends Handover Request message to target eNB.
Admission Control is performed by target eNB and target eNB configured the required resources according to the received E-RAB QoS information.
Target eNB sends Handover Request Acknowledge message to MME.
If indirect forwarding applies MME sets up Create Indirect Data Forwarding Tunnel Request to SGW. SGW responds with confirmation.
MME sends HO command (Handover Type, ERABs forwarding (optional) etc.) message to source eNB.
Source eNB sends RRC Connection Reconfiguration message to UE with necessary parameters (target eNB security algorithm, SIBs etc.).
Source eNB sends Status Transfer message via MME to target eNB regarding downlink and uplink transmitter status.
Once UE successfully synchronizes to the target cell, it sends an RRC Connection Reconfiguration Complete message to target eNB. DL packets forwarded from source eNB can be sent to the UE. Also uplink packets can be sent from UE, which are forwarded to SGW.
Target eNB sends Handover Notify message to target MME. MME starts a timer to supervise when resources in Source eNB and data forwarding resources in SGW shall be released.
MME sends Modify Bearer Request (Bearers contexts to be removed, bearers need to be deactivated, etc.) message to SGW.
SGW sends “end marker” packet to source eNB and then releases resources towards it. Once “end marker” reaches target eNB, SGW can start sending DL payload data coming from PGW. It also sends Modify Bearer Response message to MME.
FIG. 14 shows a prior art LTE X2 Based Inter eNodeB Handover diagram.
Source eNB uses X2 interface to initiate handover with target eNB. Process is somewhat similar to S1 based handover with difference that Handover request, data forwarding, End marker messages etc. are exchanged over X2 interface directly between Source and Target eNBs.
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